Two-cycle internal combustion engine



Nov. 16, 1965 c. MITROWKE 3,217,698

TWO-CYCLE INTERNAL COMBUSTION ENGINE Filed Sept. 26, 1963 2 Sheets-Sheet 1 .lll

MIH

INVENTOR CHARLES MITROWKE ATTORNEY Nov. 16, 1965 c. MITROWKE 3,217,698

TWO-CYCLE INTERNAL COMBUSTION ENGINE Filed Sept. 26. 1963 2 Sheets-Sheet 2 INVENTOR CHARLES MITROWKE BY 69M ATTORNEY 3,217,598 Patented Nov. 16, 1965 3,217,698 TWO-CYCLE INTERNAL COMBUSTIQN ENGINE Charles Mitrowire, 2525 N. 28th St., Milwaukee 10, Wis. Filed Sept. 26, 1963, Ser. No. 311,713 1 Claim. (Cl. 123-56) This invention relates to two-cycle gas engines.

The main object of this invention is to provide a twocycle gas engine having more than one piston which works off of a single crank pin, whereby a more compact engine design is provided and the weight per HR is substantially reduced.

Another object of this invention is to provide a twocycle gas engine structure in which a shorter and more rigid crankshaft is provided and may be used in the present engine assembly.

A further object of the invention is to eliminate the necessity of compartmentizing individual cranks for multiple cylinder two-cycle engines as is required in conventional two-cycle engine designs.

Other features of the invention comprehend the use of a disc piston fixed to a piston rod in connection with a closed cylinder and in which a Scotch yoke mechanism is provided for imparting rotary motion to the crankshaft, also the provision of a structure in which fuel is directly admitted to the closed end of a cylinder by the use of longitudinal grooves or passages cut into the cylinder wall structure, the grooves and the disc piston being so constructed and arranged as to permit the passage of the fuel about the piston when the latter reaches the lower end of its stroke.

These and other objects of the invention will more clearly hereinafter appear by reference to the accompanying drawings forming a part of the instant specification and wherein like characters of reference designate corresponding parts throughout the several views, in which:

FIG. 1 is a side elevation partly in section of a twocycle gas engine utilizing two cylinders;

FIG. 2 is a perspective view of the crankshaft arrangement utilizing a Scotch yoke assembly;

FIG. 3 is a fragmentary top plan view of the structure of FIG. 2; and

FIG. 4 is a front elevation of the structure of FIG. 3.

Referring to FIG. 1, a pair of cylinders 1 and 2 are indicated, cylinder 2 being shown in section together with the crankshaft housing. The cylinder 2 includes an outer cast wall having heat fins 3 and a removable cylinder head 4 formed with an elevated lateral portion 5 providing an exhaust passage 6. The cylinder head 4 is fixed by a series of bolts 7, one of which is illustrated, extending through the head and into the cylinder wall in the area of the exhaust discharge 8. A spark plug 9 is provided in the head and is positioned axially above the exhaust valve 10 carried by the valve stem 11, and the latter is provided with the usual springs 12 and extends through the crankshaft housing at 14 for operation by the cam 15 on the crankshaft 16.

The cylinder 2 is provided with a liner 17 formed with a plurality of longitudinal slots 18 at its bottom portion providing elongated passageways for the passage of fuel from the crank housing into the cylinder, as will be hereinafter more fully described. The bottom of the cylinder 2 is closed by the crankshaft housing casting extension 20 provided with a plurality of ports 21 annularly arranged about the piston rod 22 fixed to and at the center of disc piston 23 and connected to the crank pin 24 associated with a Scotch yoke 25, to be hereinafter more fully described.

It will be noted that the crankshaft housing extension 21) receiving the lower end of the cylinder 2 is provided with an annular recess 26 in which the end of the cylinder 2 and its liner 17 seat, and that the ports 21, through this crankshaft housing extension, feed the fuel into the cylinder as the piston 23 travels upward. As the piston 23 rises in the cylinder above the transfer passages 18, a vacuum will be created in the portion of the cylinder beneath the piston. This will cause the spring plate valves 28 to rise off their sea-ts and allow fuel to enter the cylinder beneath the piston from the crank housing. The fuel remains in the cylinder beneath the piston until the near completion of the next stroke of the piston. Thus, when the piston 23 reaches the top of its travel and starts descending, the spring valve 28 closes and the fuel charge beneath the piston is compressed. When the piston uncovers the transfer ports 18, the compressed charge under the piston then enters the cylinder above the piston through the transfer ports 18. Thus it will be seen that the fuel charge is taken into the cylinder under the piston through passages 21 from the crank housing and then compressed and allowed to enter the cylinder above the piston through the transfer passages 18.

The sequence requires two strokes of the piston, each stroke utilizing a separate set of passages. That is, the upstroke of the piston pulls fuel from the crank housing through the crankcase passages 21 and the down-stroke of the piston then allows the fuel to enter the cylinder above the piston through the transfer passages 18.

The ports 21 are closed by flat spring plate valves 28 fixed by bolts or other fastenings 29 to the medial portion 30 of the crankshaft housing through which the piston rod 22 extends for connection with the disc piston 23. The closed crankshaft housing includes the spaced walls and 36 and closed upper crank housing extension 20, as shown in FIG. 1. A similar crank housing extension is provided for closing the end of cylinder 1 but is not shown in the drawing, it being understood that both cylinders 1 and 2 are similarly constructed and have corresponding parts.

The crankshaft 16 includes a section 16a, the sections being in alignment and both terminating within the crankshaft housing. The crankshaft 16 at its inner end within the housing is connected axially with the flywheel 37, while the crankshaft section 1611 is connected at its inner end medially to a web-like structure or plate 40, more clearly shown in FIGS. 2 and 3, and to which web-like structure or plate the Scotch yoke 25 is associated and is provided with an elongated slot 38 in which travels the bearing 39 which receives the crank pin 24. The web-like structure 40 connects the crankshaft section 16a with the crank pin and through the crank pin with the flywheel 37.

A fuel supply source, such as a carburetor, is connected to an inlet at 41 with the crankshaft housing and will supply suitably proportioned fuel to the housing in accordance with requirements.

A disc piston 23 is fixed to the piston rod 22 and the piston rod is directly fixed to the medial portion of the Scotch yoke 25. The rectangular frame defining the Scotch yoke is medially connected with the axially aligned piston rods 22 connected to each of the oppositely arranged pistons. The Scotch yoke encloses the crank pin 24 which latter is provided with a bearing housed in a rectangular block 42, as shown in FIG. 2. It will be noted that suitable seals and bearings 43 and 44 are provided for mounting the adjacent ends of the crankshaft 16, 16a within the crankshaft housing.

It will be noted that the instant invention may be readily modified to accommodate four cylinders, all of which may operate from a single crank pin.

Referring to FIG. 1, the disc piston 23 is shown at the bottom of its travel and about to start its compression stroke to move toward the outer closed end of cylinder 2. The exhaust valve 10, due to the structure of the cam 15, has just seated. As the piston 23 moves above the upper ends of the fluid transfer passages 18 in the cylinder wall liner 17, the charge of air and fuel starts being compressed and at the same time a vacuum is being created beneath 3 the disc piston 23. The suction beneath the piston 23 will lift the spring plate valves 28 from their seat and cause a flow of fuel and air mixture from the crankcase to enter the cylinder beneath the piston and through the ports 21.

It will be understood that the charge in the crankcase is customarily replenished by a carburetor through fuel inlets 41 or through any suitable source. When the piston 23 reaches the top of its compression stroke, the charge is ignited by the spark plug 9 and the expanding gases force the piston 23 downwardly. The downward movement of the disc piston 23 closes the spring valves 28 thus stopping the further flow of air and fuel into or from the cylinder beneath the piston 23 and more particularly preventing the re-entry of the fuel charge into the crankcase. The exhaust valve 10 opens immediately before the piston 23 uncovers the transfer passages 18, thus allowing the pressure clue to the spent charge to fall to a point where a fresh charge of fuel and air may enter through the fuel ports 18 into the cylinder above the piston. As the piston moves down further, the fuel passages 18 are uncovered and the compressed charge in the cylinder under the piston rises in the cylinder through the fuel ports 18 above the piston. The movement of the crankshaft rotates the exhaust valve cam 15 allowing the exhaust valve to seat and thus complete the operating cycle of the engine.

It is to be noted that the disc-like pistons are relatively short in length and their length is proportioned to the length of the slots in the cylinder liner 17 so that proper timing of fuel entry and plate valve closing is accomplished. It will be further noted that the pistons are axially and rigidly fixed to the piston rods 22 thus eliminating a multiplicity of parts including connecting rod bearings and the like.

If preferred, the fuel can be fed from a valve chest sealingly fixed to the cylinder, the valve chest to include a valve plate for entrance of fuel into the chest and closed to prevent back-flow from the chest to the source of fuel supply. The appropriate spring plates corresponding in operation to the spring plates 28 can be provided for the transfer of fuel from the chest to the cylinder. In such an arrangement the chest will obviously be located at the bottom of the cylinder and the sequence of operation will be in accordance with the disclosure of FIG. 1; The use of a valve chest for admitting fuel to the cylinder will eliminate the use of the crank housing as a source of fuel 45 supply and the use of the chest will permit the opening of the crank housing to the atmosphere,

What I claim is:

In a two-cycle gas engine, a pair of oppositely positioned aligned cylinders each having inner and outer end walls and each provided with a disc-like piston fixedly connected to aligned piston rods, a crankcase housing including a pair of spaced opposite walls interposed between said cylinders, each of said cylinders being provided at its outer ends with an exhaust port and an exhaust valve, said cylinders being provided with cylindrical liners, said liners being formed with a plurality of circumferentially spaced longitudinally extending slots about their inner end portions, said slots extending to the inner ends of the cylinder walls, ports extending through the inner end walls of the cylinders communicating with the slots in said liners and with the interior of said crankcase, spring plate valves fixed to the inner faces of the inner end walls of said cylinders over said ports for opening and closing said ports by compression and suction produced by movement of said pistons, means for feeding fuel to the crankcase, a sectional aligned crankshaft, each crankshaft section having one of its ends extending through opposite walls of said crankcase and into said housing, a flywheel on the end portion of one shaft extremity, a transverse member fixed to the end of the other shaft and spaced from the flywheel, a crank pin connecting the end portion of the transverse member with the flywheel, a yoke member formed with an elongated slot for receiving the crank pin therein, said yoke member being connected to the inner ends of the aligned crankshafts to thereby provide a Scotch yoke assembly, cam means on the crankshaft assembly for operating the exhaust valves, and spark plugs extending through the outer heads of the cylinders.

References Cited by the Examiner UNITED STATES PATENTS 1,061,025 5/1913 TangeInOH. 1,229,217 6/1917 Brougham 123-74 1,607,431 11/1926 Brice. 1,613,528 1/1927 Palmer. 2,405,016 7/1946 Cook 12356 2,586,467 2/1952 Jacobsen 123-73 FOREIGN PATENTS 167,180 5/1922 Great Britain.

SAMUEL LEVINE, Primary Examiner.

FRED E. ENGELTHALER, Examiner. 

